The present application relates to a manufacturing apparatus and a manufacturing method of an optical sheet having translucency and three-dimensional structures on both sides thereof.
In recent years, the thickness of a liquid crystal display apparatus is being reduced. For the reduction in the thickness of a liquid crystal display apparatus, a backlight unit that illuminates a liquid crystal panel is necessary to be reduced in thickness. In view of this, a study is being made on the reduction in thickness of various optical sheets that constitute a backlight unit and a combination of optical sheets of different types.
The combination of different optical sheets of different types allows one optical sheet to have a plurality of optical functions, which can reduce the necessary number of optical sheets, to efficiently reduce the thickness of a backlight unit. As such an optical sheet, for example, an optical sheet having different shapes on the front surface and the back surface thereof is given. Further, as a manufacturing method of such an optical sheet, there has been known a method of using a pair of endless belts on each of which an embossed shape is formed (see, paragraph 0066 and FIG. 6 in Japanese Patent Application Laid-open No. 2008-260268 (hereinafter, referred to as Patent Document 1)). A resin sheet is conveyed between a heating and transfer process and a cooling and peeling process while being sandwiched between the pair of endless belts, thereby making it possible to form the embossed shape on the both sides of the resin sheet.